Gamma secretase inhibitors

ABSTRACT

Disclosed herein are compounds of Formula (I) (I) and pharmaceutically acceptable salts thereof, wherein each of the substituents is given the definition as set forth in the specification and claims. Also disclosed are pharmaceutical compositions containing the compound of Formula (I) and use of the compound in the treatment of neurodegenerative diseases or conditions such as Alzheimer&#39;s disease.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C.§371 of PCT Application No. PCT/US2012/053598, filed Sep. 4, 2012, whichclaims priority under 35 U.S.C. §119(e) from U.S. Ser. No. 61/532,842filed Sep. 9, 2011.

BACKGROUND OF THE INVENTION

Alzheimer's disease is a disease characterized by degeneration and lossof neurons and also by the formation of senile plaques andneurofibrillary change. Presently, treatment of Alzheimer's disease islimited to symptomatic therapies with a symptom-improving agentrepresented by an acetylcholinesterase inhibitor, and the basic remedywhich prevents progress of the disease has not been developed. A methodof controlling the cause of onset of pathologic conditions needs to bedeveloped for creation of the basic remedy of Alzheimer's disease.

Aβ protein, which is a metabolite of amyloid precursor protein(hereinafter referred to as APP), is considered to be greatly involvedin degeneration and loss of neurons as well as onset of dementialconditions (for example, see Klein W L, et al Proceeding NationalAcademy of Science USA, Sep. 2, 2003, 100(18), p. 10417-22), suggestinga molecular basis for reversible memory loss.

Nitsch R M, and 16 others, Antibodies againstβ-amyloid slow cognitivedecline in Alzheimer's disease, Neuron, May 22, 2003, 38(4), p. 547-554)suggest that the main components of Aβ protein are Aβ40 consisting of 40amino acids and Aβ42 having two additional amino acids at theC-terminal. The Aβ40 and Aβ42 tend to aggregate (for example, seeJarrell J T et al, The carboxy terminus of the β amyloid protein iscritical for the seeding of amyloid formation: implications for thepathogenesis of Alzheimer's disease, Biochemistry, May 11, 1993, 32(18),p. 4693-4697) and constitute the main components of senile plaques (forexample, (Glenner G G, et al, Alzheimer's disease: initial report of thepurification and characterization of a novel cerebrovascular amyloidprotein, Biochemical and Biophysical Research Communications, May 16,1984, 120(3), p. 885-90. See also Masters C L, et al, Amyloid plaquecore protein in Alzheimer's disease and Down's syndrome, ProceedingNational Academy of Science USA, June 1985, 82(12), p. 4245-4249.).

Furthermore, it is known that mutations of APP and presenelin genes,which are observed in familial Alzheimer's disease, increase productionof Aβ40 and Aβ42 (for example, see Gouras G K, et al, IntraneuronalAβ142 accumulation in human brain, American Journal of Pathology,January 2000, 156(1), p. 15-20. Also, see Scheuner D, et al, NatureMedicine, August 1996, 2(8), p. 864-870; and Forman M S, et al,Differential effects of the Swedish mutant amyloid precursor protein onβ-amyloid accumulation and secretion in neurons and nonneuronal cells,Journal of Biological Chemistry, Dec. 19, 1997, 272(51), p.32247-32253.). Therefore, compounds which reduce production of Aβ40 andAβ42 are expected to be agents for controlling progress of Alzheimer'sdisease or for preventing the disease.

These Aβs are produced when APP is cleaved by beta secretase andsubsequently cleaved by gamma secretase. In consideration of this,creation of inhibitors of γ-secretase and β-secretase has been attemptedfor the purpose of reducing production of Aβs. Many of these knownsecretase inhibitors are peptides or peptidomimetics such as L-685,458.L-685,458, an aspartyl protease transition state mimic, is a potentinhibitor of γ-secretase activity (Biochemistry, Aug. 1, 2000, 39(30),p. 8698-8704).

There is a need for new compounds, formulations, treatments andtherapies to treat diseases and disorders associated with Aβ. It is,therefore, an object of this invention to provide compounds useful inthe treatment or prevention or amelioration of such diseases anddisorders.

SUMMARY OF THE INVENTION

Compounds of this invention herein termed gamma secretase inhibitorshave the structure of Formula (I)

or a pharmaceutically acceptable salt thereof, wherein

R is a 5-6 membered heteroaryl containing 1-2 nitrogen atoms optionallysubstituted with one L¹ group; or a —(C1-C6)alkyl(5-6membered)heteroaryl containing 1-3 heteroatoms selected from N and Ooptionally substituted with one L¹ group, with the proviso that the (5-6membered)heteroaryl of the —(C1-C6)alkyl(5-6 membered)heteroaryl is notfuranyl;R¹ is independently selected from the group consisting of halogen,—(C1-C6)alkyl, —CN, —CF₃, —O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl),—C(O)—O—(C1-C6)—OH-substituted (C1-C4)alkyl, halo(C1-C6)alkyl,—(C1-C4)alkoxy-OH, —(C1-C4)alkoxy(C1-C4)alkoxy and —S(O)₂(C1-C6)alkyl; nis 0, 1, 2, or 3;Ar is selected from the group consisting of phenyl optionallysubstituted with 1 or 2 L² groups, and pyridyl optionally substitutedwith 1 or 2 L² groups;L¹ is independently selected from the group consisting of —OCH₃, —NH₂,═O, and (C1-C5)alkyl; andL² is independently selected from the group consisting of halogen,(C1-C6)alkyl, —CN, —CF₃, —O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl),—C(O)—O—(C1-C6)alkyl, —OH- substituted (C1-C6)alkyl, halo(C1-C6)alkyl,—OH-substituted (C1-C4)alkoxy, —(C1-C4)alkoxy(C1-C4)alkoxy and—S(O)₂(C1-C6)alkyl.

In an embodiment, the present invention provides for pharmaceuticalcompositions comprising at least one compound of Formula (I). In anotherembodiment, the present invention provides for methods for inhibitinggamma secretase activity comprising administering a therapeuticallyeffective amount of at least one compound of Formula (I) to a patientafflicted with a disease or condition amenable to treatment byinhibition of gamma secretase, e.g., Alzheimer's disease.

DETAILED DESCRIPTION OF THE INVENTION

As used above, and throughout this disclosure, the following terms,unless otherwise indicated, shall be understood to have the followingmeanings:

“At least one” means there is at least one, and examples include 1, 2 or3, or 1 or 2, or 1.

“One or more” means the same as “at least one.”

“Patient” and “subject” means an animal, such as a mammal, e.g., a humanbeing, and is preferably a human being.

“Alkyl” means an aliphatic hydrocarbon group, which may be straight orbranched and comprising about 1 to about 6 carbon atoms in the chain orabout 1 to about 2 or 3 carbon atoms in the chain. Branched means thatone or more lower alkyl groups such as methyl, ethyl or propyl, areattached to a linear alkyl chain. Non-limiting examples of suitablealkyl groups include methyl, ethyl, n-propyl, isopropyl and t-butyl.

“Halogen” means fluorine, chlorine, bromine, or iodine. Fluorine,chlorine and bromine are preferred. A substituent which is a halogenatom means —F, —Cl, —Br, or —I, and “halo” means fluoro, chloro, bromoor iodo substituents bonded to the moiety defined, e.g., “haloalkyl”means an alkyl, as defined above, wherein one or more of the bondingpositions on the alkyl moiety typically occupied by hydrogen atoms areinstead occupied by a halo group, e.g., trifluoromethyl.

“Heteroaryl” means an aromatic monocyclic ring system comprising about 5to about 6 ring atoms in which one or more of the atoms in the ringsystem is an element other than carbon, for example nitrogen or oxygenor in combination. Any —NH in a heteroaryl ring may exist in protectedform, for example, as an —N(Boc), —N(CBz), —N(Tos) group and the like;such protected forms are also considered part of this invention.Non-limiting examples of suitable monocyclic heteroaryl rings includepyrrole, oxazole, imidazole, pyrazole, isooxazole, 1,2,3, oxadiazole,1,2,4, oxadiazole, 1,2,3-triazole, 2H-pyran, 4H-pyran, pyridine,pyrimidine, pyridazine, pyrazine, 1,3,5, triazine, pyrrole.

“Hydroxy (—OH) substituted alkyl” means an alkyl group substituted witha hydroxy (—OH) group in which alkyl is as previously defined. Preferredhydroxyalkyls contain lower alkyl. Non-limiting examples of suitablehydroxyalkyl groups include hydroxymethyl and 2-hydroxyethyl.

“Alkoxy” means an —O—(C1-C4)alkyl group in which the alkyl group is aspreviously described. Non-limiting examples of suitable alkoxy groupsinclude methoxy, ethoxy, n-propoxy, isopropoxy and n-butoxy. The bond tothe parent moiety is through the ether oxygen.

“Alkoxyalkoxy” means (C1-C4)alkoxy-(C1-C4)alkoxy” and refers to alkoxygroups as defined above wherein at least one of the hydrogen atoms ofthe lower alkoxy group is replaced by an alkoxy group as defined above.Among the preferred lower alkoxyalkoxy groups are 2-methoxy-ethoxy and3-methoxy-propoxy.

The term “substituted” means that one or more hydrogens on thedesignated atom is replaced with a selection from the indicated group,provided that the designated atom's normal valency under the existingcircumstances is not exceeded, and that the substitution results in astable compound. Combinations of substituents and/or variables arepermissible only if such combinations result in stable compounds. By“stable compound” or “stable structure” is meant a compound that issufficiently robust to survive isolation to a useful degree of purityfrom a reaction mixture, and formulation into an efficacious therapeuticagent.

The term “optionally substituted” means optional substitution with thespecified groups, radicals or moieties. For example, a phenyl optionallysubstituted with an indicated group of substituents includesunsubstituted phenyl as well as phenyl substituted with any of theindicated substituents.

It should also be noted that any carbon atom as well as any heteroatomwith unsatisfied valences in the text, schemes, examples, Tables, etc.herein is assumed to have the sufficient number of hydrogen atom(s) tosatisfy the valences.

When a functional group in a compound is termed “protected”, this meansthat the group is present in modified form to preclude undesired sidereactions at the protected site when the compound is subjected to areaction. Suitable protecting groups will be recognized by those withordinary skill in the art as well as by reference to standard textbookssuch as, for example, T. W. Greene et al, Protective Groups in OrganicSynthesis (1991), Wiley, N.Y., herein incorporated by reference in itsentirety.

“Effective amount” or “therapeutically effective amount” is meant todescribe an amount of compound or a composition of the present inventioneffective in inhibiting the production and/or deposition of amyloidprotein, and thus producing the desired therapeutic, ameliorative,inhibitory or preventative effect.

This invention provides compounds that are inhibitors (e.g.,antagonists) of gamma-secretase (also termed “γ-secretase”) and have theFormula (I):

or a pharmaceutically acceptable salt thereof, wherein

R is a 5-6 membered heteroaryl containing 1-2 nitrogen atoms optionallysubstituted with one L¹ group; or a —(C1-C6)alkyl(5-6membered)heteroaryl containing 1-3 heteroatoms selected from N and Ooptionally substituted with one L¹ group, with the proviso that the (5-6membered)heteroaryl of the —(C1-C2)alkyl(5-6 membered)heteroaryl is notfuranyl; R¹ is independently selected from the group consisting halogen,(C1-C6)alkyl, —CN, —CF₃, —O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl),—C(O)—O—(C1-C6)—OH-substituted (C1-C4)alkyl, halo(C1-C6)alkyl,—(C1-C4)alkoxy-OH, —(C1-C4)alkoxy(C1-C4)alkoxy and —S(O)₂(C1-C6)alkyl; nis 0, 1, 2, or 3;

Ar is selected from the group consisting of phenyl optionallysubstituted with 1 or 2 L² groups, and pyridyl optionally substitutedwith 1 or 2 L² groups;

L¹ is independently selected from the group consisting of —OCH₃, —NH₂,═O, and (C1-C5)alkyl (e.g., methyl, propyl, butyl and pentyl); and

L² is independently selected from the group consisting of halogen,(C1-C6)alkyl, —CN, —CF₃, —O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl),—C(O)—O—(C1-C6)alkyl, —OH- substituted (C1-C6)alkyl, -halo(C1-C6)alkyl,—OH-substituted (C1-C4)alkoxy, —(C1-C4)alkoxy(C1-C4)alkoxy and—S(O)₂(C1-C6)alkyl.

The compounds of the invention have been found to be inhibitors ofgamma-secretase activity and are believed to be useful in providingtreatment of conditions or diseases which can be treated by inhibitionof gamma-secretase activity, for example, Alzheimer's disease, Down'sSyndrome, mild cognitive impairment, glaucoma, cerebral amyloidangiopathy, stroke, dementia, microgliosis, brain inflammation,traumatic brain injury and olfactory function loss, and certain cancers,for example, T cell acute lymphoblastic leukemia, ovarian cancer, andlung cancers, e.g., non-small-cell lung carcinomas.

In one embodiment of the compounds of Formula (I), n is 2, each R¹ isthe same or different halogen, and the R¹ groups are bound to the phenylmoiety as shown in Formula (II):

In another embodiment of the compounds of Formula (I), in particularwhen n is 2, wherein the R¹ groups are bound to the phenyl moiety asshown in Formula (II), the halogen of R¹ is fluoro.

In another embodiment of the compounds of Formula (I), in particular,when n is 2, wherein the R¹ groups are bound to the phenyl moiety asshown in Formula (II), and R¹ is fluoro, Ar is selected from the groupconsisting of p-Cl-phenyl-, p-CN-phenyl-, p-CF₃-phenyl, pyridyl, andpyridyl substituted with 1 or 2 substituents independently selected fromthe group consisting of halogen,

—(C1-C6)alkyl, —CN, —CF₃, —O—(C1-C6)alkyl, —O-halo(C1-C6)alkyl,—C(O)—O—(C1-C6)alkyl, —OH-substituted (C1-C6)alkyl, -halo(C1-C6)alkyl,—OH substituted (C1-C4)alkoxy and —(C1-C4)alkoxy(C1-C4)alkoxy.

In another embodiment of the compounds of Formula (I), in particular,when n is 2, wherein the R¹ groups are bound to the phenyl moiety asshown in Formula (II), and R¹ is fluoro, Ar is p-Cl-phenyl.

In another embodiment of the compounds of Formula (I), R is a 5-6membered heteroaryl containing 1-2 nitrogen atoms optionally substitutedwith one L¹ group.

In another embodiment of the compounds of Formula (I), the 5-6 memberedheteroaryl containing 1-2 nitrogen atoms optionally substituted with oneL¹ group is selected from pyridinyl, pyrimidinyl, pyradazinyl andpyrazinyl.

In another embodiment of the compounds of Formula (I), R is a(C1-C6)alkyl(5-6 membered)heteroaryl containing 1-3 heteroatoms selectedfrom N and O optionally substituted with one L¹ group. In particularlyuseful embodiments of the compounds of Formula (I), R is a(C1-C2)alkyl(5-6 membered)heteroaryl.

In another embodiment of the compounds of Formula (I), the (5-6membered)heteroaryl of the (C1-C6)alkyl(5-6 membered)heteroarylcontaining 1-3 heteroatoms selected from N and O optionally substitutedwith one L¹ group is selected from pyridinyl, pyrazolinyl and 1, 2, 4oxadiazolyl.

In another embodiment, the compounds of Formula (I) have the followingFormula (IA)

In another embodiment of the compounds of Formula (IA), Ar isp-Cl-phenyl, n is 2, each R¹ is the same or different halogen, and theR¹ groups are bound to the phenyl moiety as shown in Formula (II):

In another embodiment of the compounds of Formula (IA) wherein Ar isp-Cl -phenyl, n is 2, each R¹ is the same or different halogen, and theR¹ groups are bound to the phenyl moiety as shown in Formula (II), R isa (C1-C6)alkyl(5-6 membered)heteroaryl containing 1-3 heteroatomsselected from N and O optionally substituted with one L¹ group.

In another embodiment of the compounds of Formula (IA), wherein Ar isp-Cl -phenyl, n is 2, each R¹ is the same or different halogen, and theR¹ groups are bound to the phenyl moiety as shown in Formula (II), the(5-6 membered)heteroaryl of the (C1-C6)alkyl(5-6 membered)heteroaryl isselected from pyridinyl, pyrazolinyl and 1, 2, 4, oxadiazolyl.

In another embodiment, the compounds of Formula (I) are selected fromthe group consisting of compounds 4, 8a, 8b, 11, 14, 25a, 25b, 25c, 25d,25e, 25f, 25g, 25h, 27a and 27b or a pharmaceutically acceptable saltthereof. In a useful embodiment, the compounds of Formula (I) areselected from the group consisting of compounds 4 and 11 or apharmaceutically acceptable salt thereof.

The compounds of Formula (I) can form salts, which are also within thescope of this invention. Reference to a compound of Formula (I) hereinis understood to include reference to salts thereof, unless otherwiseindicated. The term “salt(s)”, as employed herein, denotes acidic saltsformed with inorganic and/or organic acids, as well as basic saltsformed with inorganic and/or organic bases. In addition, when a compoundof Formula (I) contains both a basic moiety, such as, but not limited toa pyridine or imidazole, and an acidic moiety, such as, but not limitedto a carboxylic acid, zwitterions (“inner salts”) may be formed and areincluded within the term “salt(s)” as used herein. Pharmaceuticallyacceptable (i.e., non-toxic, physiologically acceptable) salts arepreferred, a lthough other salts are also useful. Salts of the compoundsof the Formula (I) may be formed, for example, by reacting a compound ofFormula (I) with an amount of acid or base, such as an equivalentamount, in a medium such as one in which the salt precipitates or in anaqueous medium followed by lyophilization.

Exemplary acid addition salts include acetates, ascorbates, benzoates,benzenesulfonates, bisulfates, borates, butyrates, citrates,camphorates, camphorsulfonates, fumarates, hydrochlorides,hydrobromides, hydroiodides, lactates, maleates, methanesulfonates,naphthalenesulfonates, nitrates, oxalates, phosphates, propionates,salicylates, succinates, sulfates, tartarates, thiocyanates,toluenesulfonates (also known as tosylates) and the like.

Additionally, acids which are generally considered suitable for theformation of pharmaceutically useful salts from basic pharmaceuticalcompounds are discussed, for example, by P. Stahl et al, Camille G.(eds.) Handbook of Pharmaceutical Salts. Properties, Selection and Use.(2002) Zurich: Wiley-VCH; S. Berge et al, Journal of PharmaceuticalSciences (1977) 66(1) 1-19; P. Gould, International J. of Pharmaceutics(1986) 33 201-217; Anderson et al, The Practice of Medicinal Chemistry(1996), Academic Press, New York; and in The Orange Book (Food & DrugAdministration, Washington, D.C. on their website). These disclosuresare incorporated herein by reference thereto.

Exemplary basic salts include ammonium salts, alkali metal salts such assodium, lithium, and potassium salts, alkaline earth metal salts such ascalcium and magnesium salts, salts with organic bases (for example,organic amines) such as dicyclohexylamines, t-butyl amines, and saltswith amino acids such as arginine, lysine and the like. Basicnitrogen-containing groups may be quarternized with agents such as loweralkyl halides (e.g. methyl, ethyl, and butyl chlorides, bromides andiodides), dialkyl sulfates (e.g. dimethyl, diethyl, and dibutylsulfates), long chain halides (e.g. decyl, lauryl, and stearylchlorides, bromides and iodides), aralkyl halides (e.g. benzyl andphenethyl bromides), and others.

All such acid salts and base salts are intended to be pharmaceuticallyacceptable salts within the scope of the invention and all acid and basesalts are considered equivalent to the free forms of the correspondingcompounds for purposes of the invention.

Prodrugs and solvates of the compounds of the invention are alsocontemplated herein. The term “prodrug”, as employed herein, denotes acompound that is a drug precursor that, upon administration to asubject, undergoes chemical conversion by metabolic or chemicalprocesses to yield a compound of Formula (I) or a salt and/or solvatethereof. A discussion of prodrugs is provided in T. Higuchi and V.Stella, Pro-drugs as Novel Delivery Systems (1987) 14 of the A.C.S.Symposium Series, and in Bioreversible Carriers in Drug Design, (1987)Edward B. Roche, ed., American Pharmaceutical Association and PergamonPress, both of which are incorporated herein by reference thereto.

“Solvate” means a physical association of a compound of this inventionwith one or more solvent molecules. This physical association involvesvarying degrees of ionic and covalent bonding, including hydrogenbonding. In certain instances the solvate will be capable of isolation,for example when one or more solvent molecules are incorporated in thecrystal lattice of the crystalline solid. “Solvate” encompasses bothsolution-phase and isolatable solvates. Non-limiting examples ofsuitable solvates include ethanolates, methanolates, and the like. A“hydrate” is a solvate wherein the solvent molecule(s) is/are H₂O.

Compounds of Formula (I), and salts, solvates and prodrugs thereof, mayexist in their tautomeric form (for example, as an amide or iminoether). All such tautomeric forms are contemplated herein as part of thepresent invention.

All stereoisomers (for example, geometric isomers, optical isomers andthe like) of the present compounds (including those of the salts,solvates and prodrugs of the compounds as well as the salts and solvatesof the prodrugs), such as those which may exist due to asymmetriccarbons on various substituents, including enantiomeric forms (which mayexist even in the absence of asymmetric carbons), rotameric forms,atropisomers, and diastereomeric forms, are contemplated within thescope of this invention, as are positional isomers (such as, forexample, 4-pyridyl and 3-pyridyl). Individual stereoisomers of thecompounds of the invention may, for example, be substantially free ofother isomers, or may be admixed, for example, as racemates or with allother, or other selected, stereoisomers. The chiral centers of thepresent invention can have the S or R configuration as defined by theIUPAC 1974 Recommendations. The use of the terms “salt”, “solvate”“prodrug” and the like, is intended to equally apply to the salt,solvate and prodrug of enantiomers, stereoisomers, rotamers, tautomers,positional isomers, racemates or prodrugs of the inventive compounds.

Polymorphic forms of the compounds of Formula (I), and of the salts,solvates and prodrugs of the compounds of Formula (I), are intended tobe included in the present invention.

The present invention also embraces isotopically-labeled compounds ofthe present invention which are structurally identical to those recitedherein, but for the fact that a statistically significant percentage ofone or more atoms in that form of the compound are replaced by an atomhaving an atomic mass or mass number different from the atomic mass ormass number of the most abundant isotope usually found in nature, thusaltering the naturally occurring abundance of that isotope present in acompound of the invention. Examples of isotopes that can bepreferentially incorporated into compounds of the invention includeisotopes of hydrogen, carbon, nitrogen, oxygen, phosphorus, fluorine andchlorine, such as ²H, ³H, ¹³C, ¹⁴C, ¹⁵N, ¹⁸O, ¹⁷O, ³¹P, ³²P, ³⁵S, ¹⁸F,and ³⁶Cl, respectively.

Certain isotopically-labeled compounds of Formula I (e.g., those labeledwith ³H and ¹⁴C) are useful in compound and/or substrate tissuedistribution assays. Tritiated (i.e., ³H) and carbon-14 (i.e., ¹⁴C)isotopes are particularly preferred for their ease of preparation anddetection. Further, substitution with heavier isotopes such as deuterium(i.e., ²H) may afford certain therapeutic advantages resulting fromgreater metabolic stability (e.g., increased in vivo half-life orreduced dosage requirements) and hence may be preferred in somecircumstances. Isotopically labeled compounds of Formula (I) cangenerally be prepared by following procedures analogous to thosedisclosed in the Schemes and/or in the Examples herein below, bysubstituting an appropriate isotopically labeled reagent for anon-isotopically labeled reagent.

Representative compounds of the invention include but are not limited tothe compounds and Examples described herein.

The compounds according to the invention have pharmacologicalproperties; in particular, the compounds of Formula (I) can inhibitgamma-secretase, and are therefore useful in the treatment or preventionof neurodegenerative diseases, e.g., Alzheimer's disease and otherneurodegenerative diseases or conditions as described below.

Pharmaceutical compositions can comprise at least one compound ofFormula (I) or a pharmaceutically acceptable salt thereof and at leastone pharmaceutically acceptable carrier. For preparing pharmaceuticalcompositions from the compounds described by this invention, inert,pharmaceutically acceptable carriers can be either solid or liquid.Solid form preparations include powders, tablets, dispersible granules,capsules, cachets and suppositories. The powders and tablets may becomprised of from about 5 to about 95 percent active compound. Suitablesolid carriers are known in the art, e.g. magnesium carbonate, magnesiumstearate, talc, sugar or lactose. Tablets, powders, cachets and capsulescan be used as solid dosage forms suitable for oral administration.Examples of pharmaceutically acceptable carriers and methods ofmanufacture for various compositions may be found in A. Gennaro (ed.),Remington's Pharmaceutical Sciences, 18th Edition, (1990), MackPublishing Co., Easton, Pa., herein incorporated by reference in itsentirety.

Liquid form preparations include solutions, suspensions and emulsions.Water or water-propylene glycol solutions for parenteral injection oraddition of sweeteners and opacifiers for oral solutions, suspensionsand emulsions are examples. Liquid form preparations may also includesolutions for intranasal administration.

Aerosol preparations suitable for inhalation may include solutions andsolids in powder form, which may be in combination with apharmaceutically acceptable carrier, such as an inert compressed gas,e.g. nitrogen.

Also included are solid form preparations that are intended to beconverted, shortly before use, to liquid form preparations for eitheroral or parenteral administration. Such liquid forms include solutions,suspensions and emulsions.

The compounds of the invention may also be deliverable transdermally.The transdermal compositions can take the form of creams, lotions,aerosols and/or emulsions and can be included in a transdermal patch ofthe matrix or reservoir type as are conventional in the art for thispurpose.

Preferably, the pharmaceutical preparation is in a unit dosage form. Insuch form, the preparation is subdivided into suitably sized unit dosescontaining appropriate quantities of the active compound, e.g., aneffective amount to achieve the desired purpose.

The term “pharmaceutical composition” is also intended to encompass boththe bulk composition and individual dosage units comprised of more thanone (e.g., two) pharmaceutically active agents such as, for example, acompound of the present invention and an additional agent selected fromthe lists of the additional agents described herein, along with anypharmaceutically inactive excipients. The bulk composition and eachindividual dosage unit can contain fixed amounts of the afore-said “morethan one pharmaceutically active agents”. The bulk composition ismaterial that has not yet been formed into individual dosage units. Anillustrative dosage unit is an oral dosage unit such as tablets, pillsand the like. Similarly, the herein-described method of treating apatient by administering a pharmaceutical composition of the presentinvention is also intended to encompass the administration of theafore-said bulk composition and individual dosage units.

The quantity of active compound in a unit dose of preparation may bevaried or adjusted from about 0.1 mg to about 1000 mg, preferably fromabout 0.1 mg to about 750 mg, more preferably from about 0.1 mg to about500 mg, and most preferably from about 0.1 mg to about 250 mg, accordingto the particular application. The actual dosage employed may be varieddepending upon the requirements of the patient and the severity of thecondition being treated. Determination of the proper dosage regimen fora particular situation is within the skill of the art. For convenience,the total daily dosage may be divided and administered in portionsduring the day as required.

The amount and frequency of administration of the compounds of theinvention and/or the pharmaceutically acceptable salts thereof will beregulated according to the judgment of the attending clinicianconsidering such factors as age, condition and size of the patient aswell as severity of the symptoms being treated. A typical recommendeddaily dosage regimen for oral administration can range from about 0.1mg/day to about 1000 mg/day, in one to four divided doses.

As indicated above, the compounds of the invention may be useful in thetreatment of Alzheimer's disease. Accordingly, in another embodiment ofthis invention a method of treating Alzheimer's disease is providedcomprising administering to a patient in need thereof a therapeuticallyeffective amount of at least one compound of Formula (I) or apharmaceutically acceptable salt thereof.

In another embodiment of the method of treating Alzheimer's disease, themethod comprises administering to a patient in need thereof atherapeutically effective amount of at least one compound of Formula (I)or a pharmaceutically acceptable salt thereof, and a therapeuticallyeffective amount of at least one drug selected from the group consistingof BACE inhibitors; muscarinic antagonists; cholinesterase inhibitors;gamma secretase inhibitors; gamma secretase modulators; HMG-CoAreductase inhibitors; non-steroidal anti-inflammatory agents;N-methyl-D-aspartate receptor antagonists; anti-amyloid antibodies;vitamin E; nicotinic acetylcholine receptor agonists; CB1 receptorinverse agonists or CB1 receptor antagonists; an antibiotic; growthhormone secretagogues; histamine H3 antagonists; AMPA agonists; PDE4inhibitors; GABAA inverse agonists; inhibitors of amyloid aggregation;glycogen synthase kinase beta inhibitors; promoters of alpha secretaseactivity; PDE-10 inhibitors; Exelon (rivastigmine); Cognex (tacrine);Tau kinase; anti-Abeta vaccine; APP ligands; agents that upregulateinsulin cholesterol lowering agents; cholesterol absorption inhibitors;fibrates; LXR agonists; LRP mimics; nicotinic receptor agonists; H3receptor antagonists; histone deacetylase inhibitors; hsp90 inhibitors;m1 muscarinic receptor agonists; 5-HT6 receptor antagonists; mGluR1;mGluR5; positive allosteric modulators or agonists; mGluR2/3antagonists; anti-inflammatory agents that can reduce neuroinflammation;Prostaglandin EP2 receptor antagonists; PAI-1 inhibitors; and agentsthat can induce Abeta efflux.

In another embodiment, a method of treating Alzheimer's disease isprovided comprising administering a therapeutically effective amount ofat least one compound of formula (I), in combination with atherapeutically effective amount of at least one cholinesteraseinhibitor (such as, for example,(±)-2,3-dihydro-5,6-dimethoxy-2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1H-inden-1-onehydrochloride, i.e, donepezil hydrochloride, available as the Aricept®brand of donepezil hydrochloride), to a patient in need of treatment.

The invention also provides for a method of inhibiting the deposition ofamyloid beta protein in, on or around neurological tissue, the methodcomprising administering to a patient in need thereof a therapeuticallyeffective amount of at least one compound of the Formula (I) or apharmaceutically acceptable salt thereof.

As the compounds of Formula (I) inhibit gamma secretase activity, theinvention also provides for a method of inhibiting gamma secretasecomprising administering to a patient in need thereof a therapeuticallyeffective amount of at least one compound of the Formula (I) or apharmaceutically acceptable salt thereof.

As the compounds of Formula (I) in inhibiting gamma secretase activity,inhibit amyloid beta production (Aβ40 and Aβ42 production) the inventionalso provides for a method of inhibiting amyloid beta productioncomprising administering to a patient in need thereof a therapeuticallyeffective amount of at least one compound of the Formula (I) or apharmaceutically acceptable salt thereof.

The compounds of Formula (I) may also be useful in treating aneurodegenerative disease or condition selected from the groupconsisting of Down's Syndrome, mild cognitive impairment, glaucoma,cerebral amyloid angiopathy, stroke, dementia, microgliosis, braininflammation, traumatic brain injury and olfactory function loss. Themethod of treatment comprises administering to a patient in need thereofa therapeutically effective amount of at least one compound of theFormula (I) or a pharmaceutically acceptable salt thereof.

The compounds of Formula (I) or a pharmaceutically acceptable saltthereof may also be useful in treating cancers such as T-cell acutelymphoblastic leukemia, ovarian cancer, and lung cancers, e.g.,non-small-cell lung carcinomas. The method of treatment of one of theaforementioned cancers comprises administering to a patient in needthereof a therapeutically effective amount of at least one compound ofthe Formula (I) or a pharmaceutically acceptable salt thereof.

The compounds of Formula (I) may also be useful in treating theaforementioned cancers in combination with a therapeutically effectiveamount of another pharmaceutically active agent, e.g., a glucocorticoidsuch as dexamethasone.

EXAMPLES

The invention disclosed herein is exemplified by the followingpreparations and examples, which should not be construed to limit thescope of the disclosure. Alternative mechanistic pathways and analogousstructures will be apparent to those skilled in the art.

Where NMR data are presented, ¹H spectra were obtained on either aVarian VXR-200 (200 MHz, ¹H), Varian Gemini-300 (300 MHz) or XL-400 (400MHz) and are reported as ppm down field from Me4Si with number ofprotons, multiplicities, and coupling constants in Hertz indicatedparenthetically. Where LC/MS data are presented, analyses was performedusing an Applied Biosystems API-100 mass spectrometer and ShimadzuSCL-10A LC column: Altech platinum C18, 3 micron, 33 mm×7 mm ID;gradient flow: 0 min-10% CH3CN, 5 min-95% CH3CN, 7 min-95% CH3CN, 7.5min-10% CH3CN, 9 min-stop. The retention time and observed parent ionare given.

The following solvents, reagents, and conditions may be referred to bytheir abbreviations in parenthesis:

Acetyl (Ac), i.e., CH₃C(O)—

Butyl (Bu)

Cyclopropyl (Pr-c)

Dichloroethane (DCE)

Dichloromethane (DCM)

Diethyl ether (Et₂O)

Diisobutylaluminum hydride (DIBAL-H)

Dimethyl formamide (DMF)

Ethanol (EtOH)

Ethyl (Et)

Ethyl acetate (EtOAc)

High resolution mass spectrometry (HRMS)

Lithium diisopropyl amide (LDA)

Liquid chromatography/mass spectrometry (LCMS)

m-Chloroperoxybenzoic acid (mCPBA)

Mesyl (Ms), i.e., —S(O)₂CH₃

Methanol (MeOH)

Methyl (Me)

Nuclear magnetic resonance spectroscopy (NMR)

Preparative thin-layer chromatography (PTLC)

Pyridine (Pyr)

Room temperature (RT)

Tert-butyldimethylsilyl (TBS)

Tetrabutyl ammonium fluoride (TBAF)

Tetrahydrofuran (THF)

Trifluoroacetic acid (TFA)

Trimethylsilyl (TMS)

Trimethylsilyl chloride (TMSCl)

Triethylamine (NEt₃ or Et₃N)

Experimental Methods

Unless otherwise noted, reagents and solvents were used as received fromcommercial suppliers. Proton nuclear magnetic resonance (NMR) spectrawere obtained on Bruker AVANCE 300 or 500 MHz spectrometers. Spectraldata is reported on a ppm (δ) scale relative to tetramethylsilane usedas an internal standard. Coupling constants are reported in hertz.

Purification by Preparative High Pressure Liquid Chromatography (Prep.HPLC) was performed on a Waters Symmetry C18 7 μm (19×300 mm) columnwith solvent gradient program described in Method 1.

Method 1

Time Flow (min) (mL/min) % A % B 0.0 20.0 90 10 15.0 20.0 0 100 18.020.0 0 100 A = Water with 0.025% v/v Hydrochloric Acid B = AcetonitrileUV Detection @ 254 nmHigh Pressure Liquid Chromatography (HPLC) analyses were obtained usinga Waters Symmetry C18 5 μm (4.6×250 mm) column with solvent gradientprograms described in Method 2.

Method 2

Time Flow (min) (mL/min) % A % B 0.0 1.0 90 10 15.0 1.0 0 100 20.0 1.0 0100 A = Water with 0.1% v/v Trifluoroacetic Acid B = Acetonitrile with0.1% v/v Trifluoroacetic Acid UV Detection @ 254 nmLiquid Chromatography-Mass Spectroscopy (LC-MS) were obtained using aSunFire C18 5 μm (4.6×50 mm) column with solvent gradient programdescribed in Method 3.

Method 3

Time Flow (min) (mL/min) % A % B 0.0 1.0 90 10 4.0 1.0 0 100 6.0 1.0 0100 A = Water with 0.05% v/v Trifluoroacetic Acid B = Acetonitrile with0.05% v/v Trifluoroacetic Acid UV Detection @ 254 nmMass Spectra were obtained on a Finnigan LCQ Duo LCMS ion trapelectrospray ionization (ESI) mass spectrometer or a Waters ACQUITY UPLCLCMS ion trap atmospheric pressure chemical ionization (APCI) massspectrometer.Optical rotation data was obtained on a Perkin Elmer 341 polarimeter.Compounds of Formula (I) can be prepared according to the procedureoutlined in General Procedure 1.

Step 1

To a solution of 0.4 g (0.74 mmol) of compound 1 (WO 2009/008980) in 7mL of dichloromethane were added 0.24 g (3.0 mmol) of pyridine and 0.23g (2.0 mmol) of methanesulfonyl chloride. The mixture was stirred atroom temperature for 3 h, and concentrated. The residue was purified bychromatography eluting with 10% to 70% ethyl acetate in hexanes to give0.38 g of compound 2. ¹H NMR (CDCl₃ 400 MHz) δ 7.62 (d, J=8.8H, 2H),7.50 (d, J=8.8 Hz, 2H), 7.10 (m, 1H), 6.44 (m, 1H), 5.16 (dd, J=12.8,2.8 Hz, 1H), 4.61 (t, J=5.6 Hz, 2H), 4.44 (d, J=12.8 Hz, 1H), 3.86 (m,1H), 3.35 (m, 4H), 3.10 (m, 2H), 3.05 (s, 3H), 2.55 (m, 2H), 2.43 (m,1H), 2.28 (m, 1H), 2.02 (m, 1H). MS: Calcd. for C₂₃H₂₆ClF₂O₉S₃ (MH⁺),615.0. found 615.3. Retention time: 5.38/9 min.

Step 2

A mixture of 0.65 g (0.11 mmol) of the mesylate 2 and 0.4 g (0.4 mmol)of triethylamine in 6 mL of dichloromethane was stirred at roomtemperature for 18 h. The mixture was purified by chromatography elutingwith 0% to 100% ethyl acetate in hexanes to give 0.56 g of compound 3.¹H NMR (CDCl₃ 400 MHz) δ 7.61 (d, J=8.4H, 2H), 7.50 (d, J=8.4 Hz, 2H),7.08 (m, 1H), 6.60 (dd, J=16.4, 10.0 Hz, 1H), 6.45 (m, 2H), 6.18 (d,J=10 Hz, 1H), 5.15 (dd, J=12.4, 2.4 Hz, 1H), 4.40 (d, J=12.4 Hz, 1H),3.87 (m, 1H), 2.95-3.33 (m, 4H), 3.10 (m, 3H), 2.75 (m, 4H), 2.30 (m,2H), 1.95 (m, 1H). MS: Calcd. for C₂₂H₂₂ClF₂O₆S₂ (MH⁺), 519.1. found519.3. Retention time: 3.02/5.5 min.

Step 3

To a solution of 0.025 g (0.05 mmol) of compound 3 in 5 mL of THF wereadded 0.03 g (0.45 mmol) of pyrazole and trace amount of powdered NaOH.The mixture was stirred at room temperature for 1 h, and concentrated.The residue was purified by chromatography eluting with a gradient of 0to 10% MeOH in CH₂Cl₂ plus 1% NH₄OH to give 0.025 g of compound 4. ¹HNMR (CDCl₃ 400 MHz) δ 7.61 (d, J=8.4H, 2H), 7.60 (m, 2H), 7.49 (d, J=8.8Hz, 2H), 7.08 (m, 1H), 6.44 (m, 1H), 6.23 (m, 1H), 5.07 (dd, J=12.8, 2.4Hz, 1H), 4.58 (t, J=6.4 hz, 2H), 4.34 (d, J=12.8 Hz, 1H), 3.80 (m, 1H),3.62 (m, 1H), 3.57 (m, 1H), 3.0-3.20 (m, 2H), 2.70 (m, 1H), 2.40 (m,2H), 2.20 (m, 1H), 1.85 (m, 1H). MS: Calcd. for C₂₅H₂₆ClF₂N₂O₆S₂ (MH⁺),587.1. found 587.3. Retention time: 2.92/5.5 min.

Step 1

A mixture of 1.0 g (1.6 mmol) of optically pure (−) compound 5 (WO2009/008980) and 0.7 g (6.2 mmol) of potassium thioacetate in 10 mL ofDMF was heated at 100° C. for 1.5 h, and cooled to room temperature. Itwas diluted with 50 mL of water, extracted with two 60 mL portions ofethyl acetate. The combined organic extracts were washed with 20 mL ofbrine, and concentrated. The residue was purified by SiO₂ chromatographyeluting with 0% to 50% ethyl acetate in hexanes to give 0.78 g ofcompound 6. ¹H NMR (CD₃OD 400 MHz) δ7.62 (d, J=8.8H, 2H), 7.49 (d, J=8.8Hz, 2H), 7.08 (m, 1H), 6.44 (m, 1H), 5.12 (dd, J=12.8, 2.8 Hz, 1H), 4.43(d, J=12.8 Hz, 1H), 3.88 (dq, J=10.0, 2.0 Hz, 1H), 3.28 (m, 2H), 3.10(m, 2H), 2.83 (m, 1H), 2.55 (m, 2H), 2.30 (s, 3H), 2.25 (m, 1H), 2.04(m, 1H), 1.83 (m, 1H). MS: Calcd. for C₂₂H₂₂ClF₂NO₅S₂ (MH⁺), 503.1.found 503.3. Retention time: 5.23/7.5 min.

Steps 2 and 3

To a suspension of 0.09 g (0.18 mmol) of compound 6 in 6 mL of anhydrousMeOH were added 0.042 g (0.6 mmol) of KOMe and 0.052 g (0.2 mmol) of2-(bromomethylpyridine) hydrobromide salt. After 20 min., it was dilutedwith 60 mL of methylene chloride, washed with 20 mL of water and 20 mLof brine. It was concentrated; the residue was redissolved in 12 mL ofmethylene chloride. To this solution were added 0.6 mL of TFA and 0.30 g(70%, 1.2 mmol) of mCPBA. The mixture was stirred at room temperaturefor 2 h, then quenched with 10 mL of 10% Na₂S₂O₃, 10 mL of 1 N NaOH, and30 mL of water. It was extracted with two 40 mL portions of methylenechloride. The combined organic extracts were concentrated; the residuewas purified by chromatography eluting with 0 to 70% ethyl acetate inhexanes to give 0.089 g (%) of compound 8a. ¹H NMR (CD₃OD 400 MHz) δ8.58 (d, J=4.4 Hz, 1H), 8.74 (t, J=6.4 Hz, 1H), 7.61 (d, J=8.8H, 2H),7.50 (m, 3H), 7.32 (m, 1H), 7.08 (m, 1H), 6.44 (m, 1H), 5.13 (dd,J=12.8, 2.4 Hz, 1H), 4.46 (d, J=12.8 Hz, 1H), 4.39 (d, J=5.2 Hz, 2H),3.86 (m, 1H), 3.20-3.40 (m, 2H), 3.09 9t, J=10.8 Hz, 1H), 2.98 (m, 1H),2.50 (m, 2H), 2.20-2.40 (m, 2H), 2.03 (m, 1H). MS: Calcd. forC₂₆H₂₅ClF₂NO₆S₂ (MH⁺), 584.1. found 584.3. Retention time: 4.24/7.5 min.

The following analog was prepared analogously:

¹H NMR (CD₃OD 400 MHz) δ 8.62 (d, J=3.6 Hz, 1H), 8.56 (s, 1H), 7.80 (m,1H), 7.61 (d, J=8.4H, 2H), 7.49 (d, J=8.4 Hz, 2H), 7.36 (m, 1H), 7.08(m, 1H), 6.45 (m, 1H), 5.13 (dd, J=12.8, 2.8 Hz, 1H), 4.39 (d, J=12.8Hz, 1H), 4.20 (s, 2H), 3.84 (m, 1H), 3.25 (m, 1H), 3.0-3.20 (m, 2H),2.85 (m, 1H), 2.52 (m, 2H), 2.40 (m, 1H), 2.28 (m, 1H), 2.0 (m, 1H). MS:Calcd. for C₂₆H₂₅ClF₂NO₆S₂ (MH⁺), 584.1. found 584.3. Retention time:3.39/7.5 min.

Step 1

A mixture of 0.26 g (0.516 mmol) of compound 6, 0.01 g (0.258 mmol) ofsodium borohydride, and 0.142 g (1.03 mmol) of potassium carbonate in5.2 mL of methanol was stirred at room temperature for 20 min. To themixture was added 0.122 g (1.03 mmol) of 2-chloromethyloxadiazole andthe reaction was stirred for an additional 30 min. The reaction wasquenched with 10 mL of saturated aqueous ammonium chloride and extractedwith three 10 mL of methylene chloride. The combined extracts were driedover anhydrous magnesium sulfate, filtered, and concentrated underreduced pressure to give 0.309 g of crude sulfide products 9 and 10,which were used directly without further purification: 9: MS Calcd. forC₂₃H₂₁ClF₂N₂NaO₅S₂ (MNa)⁺, m/z=565.0. found 565.0. Retention time: 3.24min.

10: ¹H NMR (CD₃OD 400 MHz) δ 7.62 (d, J=8.8H, 2H), 7.50 (d, J=8.8 Hz,2H), 7.08 (m, 1H), 6.46 (m, 1H), 5.15 (dd, J=12.4, 2.4 Hz, 1H), 4.41 (d,J=12.4 Hz, 1H), 3.87 (m, 1H), 3.36 (m, 4H), 3.29 (s, 2H), 3.15 (m, 1H),2.95 (m, 1H), 2.78 (m, 1H), 2.55 (m, 2H), 2.30 (m, 1H), 2.18 (m, 1H),1.95 (m, 1H). MS: Calcd. for C₂₂H₂₁ClF₂NO₄S₂ (MH⁺), 500.1. found 500.3.Retention time: 5.87/9.0 min.

Step 2

The crude sulfide products 9 and 10 were dissolved in 5.7 mL ofmethylene chloride. To the resulting solution was added 0.13 g (1.14mmol) of trifluoroacetic acid and 0.394 g (70%, 1.59 mmol) of3-chloroperoxybenozic acid. The reaction was stirred at room temperaturefor 1.5 h. After this time, the reaction was diluted with 10 mL ofmethylene chloride and washed with three 10 mL portions of saturatedaqueous sodium bicarbonate, dried over anhydrous magnesium sulfate,filtered, and concentrated under reduced pressure. The residue waspurified by column chromatography (silica, 10-60% EtOAc/heptane) toafford 0.076 g (27%) of compound 11 as a white solid: ¹H NMR (DMSO-d₆500 MHz) δ 9.71 (s, 1H), 7.67-7.81 (m, 4H), 7.42 (td, J=9.8, 4.7 Hz,1H), 6.76 (ddd, J=12.8, 9.2, 3.9 Hz, 1H), 4.86-5.02 (m, 3H), 4.59 (d,J=12.7 Hz, 1H), 3.84-3.99 (m, 1H), 3.38-3.49 (m, 1H), 3.25-3.36 (m, 2H),3.05 (t, J=11.8 Hz, 1H), 2.55 (d, J=13.8 Hz, 1H), 2.41 (d, J=10.2 Hz,1H), 2.28-2.38 (m, 1H), 2.16 (t, J=11.7 Hz, 1H), 1.92-2.06 (m, 1H). MS:Calcd. for C₂₃H₂₁ClF₂N₂NaO₇S₂ (MNa)⁺, m/z=597.0. found 597.0. HPLC(Method 2) 96.1% (AUC), t_(R)=15.66 min. [α]²⁰ _(D)=−129.5° (c 0.23,DMSO).

Step 1

A solution of 0.103 g (0.205 mmol) of compound 6, 0.004 g (0.10 mmol) ofsodium borohydride, and 0.057 g (0.41 mmol) of potassium carbonate in2.1 mL of methanol was stirred at room temperature for 20 min. To thissolution was added 0.054 g (0.41 mmol) of compound 12, and the reactionwas stirred for 1 h. After this time, the reaction was quenched with 10mL of saturated aqueous ammonium chloride and extracted with three 10 mLof methylene chloride. The combined organics were dried over anhydrousmagnesium sulfate, filtered, and concentrated to afford the crudeproduct 13 which was used directly without further purification: MS:Calcd. for C₂₄H₂₃ClF₂N₂NaO₅S₂ (MNa⁺), m/z=579.1. found 579.1. Retentiontime: 2.31 min.

Step 2

To a stirred solution of crude product 13 in 4 mL of methylene chloridewas added 0.142 g (70%, 0.57 mmol) of 3-chloroperoxybenozic acid. Thereaction was stirred at room temperature for 15 h. After this time, thereaction was diluted with 15 mL of methylene chloride and washed withthree 10 mL of saturated aqueous sodium bicarbonate, dried overanhydrous magnesium sulfate, filtered, and concentrated. The residue waspurified by flash chromatography (silica, 10-80% ethyl acetate/heptane)to afford 0.08 g (66% over two steps) of compound 14 as a white solid:¹H NMR (DMSO-d₆ 500 MHz) δ 7.83-7.69 (m, 4H), 7.47-7.37 (m, 1H),6.84-6.67 (m, 1H), 4.93 (dd, J=12.8, 2.5 Hz, 1H), 4.82 (q, J=14.7 Hz,2H), 4.60 (d, J=12.7 Hz, 1H), 3.92 (d, J=11.7 Hz, 1H), 3.48-3.36 (m,1H), 3.35-3.21 (m, 1H), 3.05 (t, J=11.8 Hz, 1H), 2.62 (s, 3H), 2.57-2.52(m, 1H), 2.42 (d, J=10.1 Hz, 1H), 2.39-2.26 (m, 1H), 2.17 (t, J=11.8 Hz,1H), 2.07 (s, 1H), 2.04-1.91 (m, 1H). MS: Calcd. for C₂₄H₂₇ClF₂N₃O₇S₂(MNH₄ ⁺), m/z=606.1. found 606.2. HPLC (Method 2) 96.9% (AUC),t_(R)=15.92 min. [α]²⁰ _(D)=−85.2° (c 0.250, DMSO).

Step 1

To a stirred solution of 2.00 g (10.6 mmol) of compound 15 in 60 mL ofTHF at −78° C. under nitrogen was added 5.5 mL (2.5 M in hexanes, 13.8mmol) of n-butyllithium dropwise and the mixture was stirred at thistemperature for 30 min. After this time, 1.70 g (53.0 mmol) of sulfurwas added and the reaction mixture was warmed to room temperature over 1h. After this time, the reaction was quenched with 15 mL of saturatedaqueous ammonium chloride and 10 mL of water and the layers wereseparated. The aqueous layer was extracted with four 15 mL portions ofmethylene chloride. The combined organics were washed with two 10 mLportions of water and 10 mL of brine, dried over anhydrous magnesiumsulfate, filtered, and concentrated to afford crude 0.86 g (58%) ofcompound 16, which was used in the subsequent step without furtherpurification: ¹H NMR (CDCl₃ 500 MHz) δ 8.20 (s, 1H), 7.73 (m, 1H), 6.69(d, J=5.0 Hz, 1H), 3.92 (s, 3H).

A suspension of 0.508 g (4.44 mmol) of compound 17 and 0.338 g (4.44mmol) of thiourea in 18 mL of ethanol was heated at 90° C. for 2 h.After this time, the reaction mixture was cooled to room temperature andconcentrated. To the residue was added 30 mL of water, followed by 0.235g (2.22 mmol) of sodium carbonate and the resulting solution wasextracted with four 25 mL portions of methylene chloride. The combinedorganics were dried over anhydrous sodium sulfate, filtered, andconcentrated to afford 0.34 g (68%) of compound 18 as a dark-yellowsolid: MS: Calcd. for C₄H₅N₂S (MH⁺), m/z=113.0. found 113.0. Retentiontime: 1.56 min.

The following compound was prepared analogously:

¹H NMR (CDCl₃ 500 MHz) δ 11.73 (s, 1H), 8.13 (s, 1H), 7.85 (d, J=6.2 Hz,1H), 7.32 (dd, J=6.2, 1.0 Hz, 1H).

Step 1

A stirred solution of 2.00 g (12.6 mmol) of compound 20 and 1.76 g (25.2mmol) of sodium methanethiolate in 10 mL of DMF was heated at 90° C.under nitrogen for 1 h. The reaction was cooled to room temperature andpoured into 20 mL of ice water. The aqueous layer was extracted with two20 mL portions of ethyl acetate and the combined organics were driedover anhydrous sodium sulfate, filtered, and concentrated under reducedpressure. The residue was purified by flash chromatography (silica,0-20% ethyl acetate/hexanes) to afford 1.36 g (86%) of compound 21 as ayellow brown solid: ¹H NMR (CDCl₃ 300 MHz) δ 8.99 (s, 1H), 8.62 (s, 2H),2.54 (s, 3H). MS: Calcd. for C₅H₇N₂(MH⁺), m/z=127.0. found 127.4.

Step 2

To a stirred solution of 1.36 g (10.8 mmol) of compound 21 in 50 mL ofliquid ammonia condensed from ammonia gas at −78° C. under nitrogen, wasadded sodium metal and the reaction was stirred vigorously until thesolution was blue. The solution was warmed to room temperature andstirred overnight. Liquid ammonia evaporated overnight affording a brownresidue. The residue was dissolved in 50 mL of water and washed with 50mL of diethyl ether. The aqueous layer was concentrated under reducedpressure to afford 1.40 g (99%) of compound 22 as a yellow solid: ¹H NMR(CDCl₃ 500 MHz) δ 8.56 (s, 2H), 8.45 (s, 1H).

Step 1

A mixture of 0.059 g (0.417 mmol) of crude 16 and 0.048 g (2.09 mmol) ofsodium ethoxide in 4.2 mL of ethanol was stirred at room temperature for30 min. After this time, 0.25 g (0.417 mmol) of compound 5 was added andthe reaction mixture was heated at 70° C. for 2 h. The reaction mixturewas cooled to room temperature, concentrated, and the residue waspartitioned between 50 mL of saturated aqueous ammonium chloride and 50mL of methylene chloride. The aqueous layer was extracted with three 15mL portions of methylene chloride. The combined organics were dried overanhydrous magnesium sulfate, filtered, and concentrated. The resultingresidue was purified by column chromatography (silica, 0-30% ethylacetate/heptane) to afford 0.166 g (70%) of compound 23a as a whitesolid: MS: Calcd. for C₂₆H₂₅ClF₂NO₅S₂ (MH⁺), m/z=568.1. found 568.0.Retention time: 2.59 min.

The following compounds were prepared analogously:

MS: Calcd. for C₂₄H₂₂ClF₂N₂O₄S₂ (MH⁺), m/z=539.1. found 539.1. Retentiontime: 2.30 min.

MS: Calcd. for C₂₄H₂₂ClF₂N₂O₄S₂ (MH⁺), m/z=539.1. found 539.0. Retentiontime: 2.31 min.

MS: Calcd. for C₂₄H₂₂ClF₂N₂O₄S₂ (MH⁺), m/z=539.1. found 539.1. Retentiontime 2.10 min.

MS: Calcd. for C₂₄H₂₂ClF₂N₂O₄S₂ (MH⁺), m/z=539.1. found 539.0.

¹H NMR (CDCl₃ 500 MHz) δ 8.42 (d, J=1.5 Hz, 1H), 8.36-8.35 (m, 1H), 8.20(d, J=1.5 Hz, 1H), 7.63 (d, J=8.5 Hz, 2H), 7.51 (d, J=8.5 Hz, 1H),7.11-7.08 (m, 1H), 6.48-6.43 (m, 1H), 5.15 (dd, J=13.0, 3.0 Hz, 1H),4.47 (d, J=12.5 Hz, 1H), 3.94-3.90 (m, 1H), 3.44-3.38 (m, 2H), 3.18-3.09(m, 2H), 2.65-2.63 (m, 1H), 2.52 (d, J=13.5 Hz, 1H), 2.35-2.29 (m, 1H),2.27-2.20 (m, 1H), 2.06-1.98 (m, 1H).

¹H NMR (CDCl₃ 500 MHz) δ 9.01 (s, 1H), 8.66 (s, 2H), 7.63 (d, J=8.5 Hz,2H), 7.51 (d, J=8.5 Hz, 2H), 7.14-7.09 (m, 1H), 6.50-6.45 (m, 1H), 5.14(dd, J=12.5, 2.5 Hz, 1H), 4.35 (d, J=12.5 Hz, 1H), 3.90-3.86 (m, 1H),3.45-3.38 (m, 1H), 3.18-3.13 (m, 1H), 3.10-3.05 (m, 1H), 3.01-2.96 (m,1H), 2.56 (d, J=10.5 Hz, 1H), 2.51 (d, J=10.5 Hz, 1H), 2.32-2.25 (m,1H), 2.19-2.12 (m, 1H), 1.93-1.86 (m, 1H).

Step 2

A mixture of 0.166 g (0.292 mmol) of compound 23a and 0.034 g (0.292mmol) of pyridine hydrochloride was heated at 175° C. for 10 min. Afterthis time, the reaction mixture was cooled to room temperature, dilutedwith 5 mL of 1 N hydrochloric acid and 10 mL of methylene chloride, andthe layers were separated. The aqueous layer was extracted with three 15mL portions of methylene chloride. The combined organics were washedwith two 10 mL portions of water and 10 mL of brine, dried overanhydrous magnesium sulfate, filtered, and concentrated. The residue waspurified by flash chromatography (silica, 0-40% ethyl acetate/heptane)to afford 0.111 g (68%) of compound 24 as a white solid: MS: Calcd. forC₂₅H₂₃ClF₂NO₅S₂ (MH⁺), m/z=554.1. found 554.1. Retention time: 2.07 min.

Step 3

To a solution of 0.111 g (0.20 mmol) of compound 24 in 2 mL of methylenechloride was added 0.173 g (70%, 0.7 mmol) of 3-chloroperbenzoic acid(mCPBA) and the mixture was stirred at room temperature for 3 h. Afterthis time, the reaction was quenched with 20 mL of saturated aqueoussodium bicarbonate. The layers were separated and the aqueous layer wasextracted with three 15 mL portions of methylene chloride. The combinedorganics were dried over anhydrous magnesium sulfate, filtered, andconcentrated. The residue was purified by flash chromatography (silica,0-40% methanol/methylene chloride) to afford 0.058 g (50%) of compound25a as a white solid: ¹H NMR (DMSO-d₆ 300 MHz) δ 12.36 (s, 1H), 7.91 (d,J=2.6 Hz, 1H), 7.82-7.58 (m, 5H), 7.49-7.33 (m, 1H), 6.83-6.67 (m, 1H),6.43 (d, J=9.7 Hz, 1H), 4.96-4.82 (m, 1H), 4.50 (d, J=12.8 Hz, 1H), 3.86(d, J=11.6 Hz, 1H), 3.42-3.13 (m, 3H), 2.97 (t, J=11.8 Hz, 1H),2.48-2.32 (m, 2H), 2.24-2.09 (m, 2H), 1.89-1.71 (m, 1H). MS: Calcd. forC₂₅H₂₃ClF₂NO₇S₂ (MH⁺) m/z=586.1. found 586.0. Retention time: 2.73 min.HPLC (Method 2) 97.5% (AUC), t_(R)=13.86 min.

The following compounds were prepared analogously according to Scheme 4,step 2:

¹H NMR (DMSO-d₆ 500 MHz) δ 9.52 (dd, J=5.1, 1.3 Hz, 1H), 8.29 (dd,J=8.5, 1.3 Hz, 1H), 8.17-8.00 (m, 1H), 7.75-7.70 (m, 4H), 7.41 (td,J=9.8, 4.6 Hz, 1H), 6.85-6.66 (m, 1H), 4.87 (dd, J=12.8, 2.3 Hz, 1H),4.46 (d, J=12.8 Hz, 1H), 3.84 (d, J=12.0 Hz, 1H), 3.79-3.59 (m, 2H),3.22 (td, J=9.8, 2.2 Hz, 1H), 2.93 (t, J=11.9 Hz, 1H), 2.37 (d, J=10.1Hz, 1H), 2.33-2.17 (m, 1H), 2.17-2.01 (m, 2H), 1.97-1.83 (m, 1H). MS:Calcd. for C₂₄H₂₁ClF₂N₂NaO₆S₂ (MNa⁺) m/z=593.0. found 593.1. Retentiontime: 2.96 min. HPLC (Method 2)>99% (AUC), t_(R)=18.16 min. [α]²⁰_(D)=−54.6° (c 0.150, DMSO).

¹H NMR (CDCl₃ 500 MHz) δ 9.39 (d, J=1.2 Hz, 1H), 9.12 (d, J=5.0 Hz, 1H),8.01 (dd, J=5.0, 1.3 Hz, 1H), 7.62 (d, J=8.6 Hz, 2H), 7.53-7.47 (m, 2H),7.11 (td, J=9.4, 4.7 Hz, 1H), 6.50-6.38 (m, 1H), 5.15 (dd, J=12.7, 2.6Hz, 1H), 4.37 (d, J=12.7 Hz, 1H), 3.89-3.78 (m, 1H), 3.76-3.64 (m, 1H),3.55-3.39 (m, 1H), 3.32 (td, J=9.7, 2.8 Hz, 1H), 3.08 (t, J=11.7 Hz,1H), 2.56-2.49 (m, 1H), 2.46-2.35 (m, 1H), 2.27 (dd, J=16.8, 7.3 Hz,1H), 2.10-1.98 (m, 1H). MS: Calcd. for C₂₄H₂₂ClF₂N₂O₆S₂ (MH), m/z=571.0.found 571.2. HPLC (Method 2) 99.0% (AUC), t_(R)=15.71 min. [α]²³_(D)=−91.3° (c 0.230, Acetonitrile).

¹H NMR (CDCl₃ 500 MHz) δ 9.60 (s, 1H), 9.56 (d, J=5.2 Hz, 1H), 7.91 (dd,J=5.2, 2.3 Hz, 1H), 7.61 (d, J=8.5 Hz, 2H), 7.51 (d, J=8.7 Hz, 2H), 7.12(td, J=9.4, 4.7 Hz, 1H), 6.51-6.35 (m, 1H), 5.17 (dd, J=12.7, 2.4 Hz,1H), 4.37 (d, J=12.6 Hz, 1H), 3.89-3.70 (m, 1H), 3.48-3.33 (m, 1H),3.33-3.18 (m, 2H), 3.00 (t, J=11.9 Hz, 1H), 2.50 (m, 2H), 2.45-2.33 (m,1H), 2.24 (t, J=12.0 Hz, 1H), 2.03-1.82 (m, 1H). MS: Calcd. forC₂₄H₂₂ClF₂N₂O₆S₂ (MH⁺), m/z=571.1. found 571.2. HPLC (Method 2) 97.2%(AUC), t_(R)=15.19 min. [α]²³ _(D)=−137.0° (c 0.150, Chloroform).

¹H NMR (CDCl₃ 500 MHz) δ 8.96 (d, J=5.0 Hz, 2H), 7.62 (d, J=8.5 Hz, 2H),7.58 (t, J=5.0 Hz, 1H), 7.51 (d, J=8.5 Hz, 2H), 7.13-7.08 (m, 1H),6.49-6.45 (m, 1H), 5.14 (dd, J=12.5, 3.0 Hz, 1H), 4.39 (d, J=11.0 Hz,1H), 3.89-3.78 (m, 2H), 3.55-3.49 (m, 1H), 3.40-3.35 (m, 1H), 3.12 (t,J=11.5 Hz, 1H), 2.57-2.46 (m, 3H), 2.46-2.31 (m, 1H), 2.14-2.10 (m, 1H).MS: Calcd. for C₂₄H₂₁ClF₂N₂NaO₆S₂ (MNa⁺), m/z=593.0. found 593.3.Retention time: 3.00 min. HPLC (Method 2) 95.7% (AUC), t_(R)=15.53 min.[α]²⁵ _(D)=−197.0° (c 0.120, Methylene Chloride).

¹H NMR (CDCl₃ 500 MHz) δ 9.29 (d, J=1.0 Hz, 1H), 8.88 (d, J=2.0 Hz, 1H),8.73-8.72 (m, 1H), 7.61 (d, J=8.5 Hz, 2H), 7.50 (d, J=8.5 Hz, 2H),7.12-7.08 (m, 1H), 6.49-6.46 (m, 1H), 5.14 (dd, J=13.0, 3.0 Hz, 1H),4.37 (d, J=12.5 Hz, 1H), 3.86-3.82 (m, 1H), 3.69-3.63 (m, 1H), 3.44-3.38(m, 1H), 3.34-3.29 (m, 1H), 3.10-3.05 (m, 1H), 2.55-2.49 (m, 2H),2.45-2.38 (m, 1H), 2.29-2.23 (m, 1H), 2.06-1.99 (m, 1H). MS: Calcd. forC₂₄H₂₁ClF₂N₂NaO₆S₂ (MNa⁺), m/z=593.0. found 593.0. Retention time: 3.00min. HPLC (Method 2)>99% (AUC), t_(R)=15.86 min. [α]²⁰ _(D)=−134.0° (c0.100, Methylene Chloride).

¹H NMR (CDCl₃ 500 MHz) δ 9.46 (s, 1H), 9.18 (s, 2H), 7.61 (d, J=8.5 Hz,2H), 7.51 (d, J=8.5 Hz, 2H), 7.13-7.09 (m, 1H), 6.49-6.44 (m, 1H), 5.17(dd, J=12.5, 2.5 Hz, 1H), 4.38 (d, J=12.5 Hz, 1H), 3.84-3.80 (m, 1H),3.45-3.39 (m, 1H), 3.30-3.19 (m, 2H), 3.06-3.02 (m, 1H), 2.54-2.46 (m,2H), 2.44-2.37 (m, 1H), 2.28-2.21 (m, 1H), 2.01-1.93 (m, 1H). MS: Calcd.for C₂₄H₂₁ClF₂N₂NaO₆S₂ (MNa⁺), m/z=593.0. found 592.9. Retention time:3.03 min. HPLC (Method 2)>99% (AUC), t_(R)=18.28 min. [α]²⁰ _(D)=−169.0°(c 0.100, Methylene Chloride).

¹H NMR (CDCl₃ 500 MHz) δ 8.67 (d, J=2.4 Hz, 1H), 7.97 (dd, J=8.8, 2.5Hz, 1H), 7.62 (d, J=8.5 Hz, 2H), 7.51 (d, J=8.7 Hz, 2H), 7.11 (td,J=9.4, 4.7 Hz, 1H), 6.86 (d, J=8.8 Hz, 1H), 6.54-6.36 (m, 1H), 5.14 (dd,J=12.7, 2.5 Hz, 1H), 4.37 (d, J=12.6 Hz, 1H), 4.03 (s, 3H), 3.90-3.78(m, 1H), 3.39-3.21 (m, 2H), 3.21-3.10 (m, 11-1), 3.05 (t, J=11.8 Hz,1H), 2.58-2.44 (m, 2H), 2.44-2.29 (m, 1H), 2.29-2.17 (m, 1H), 1.99-1.82(m, 1H). MS: Calcd. for C₂₆H₂₅ClF₂NO₇S₂ (MH⁺), m/z=600.1. found 600.1.HPLC (Method 2)>99% (AUC), t_(R)=16.93 min. [α]²³ _(D)=−67.8° (c 0.150,Acetonitrile).

Step 1

To a stirred solution of 0.050 g (0.20 mmol) of3,3′-disulfanediyldipyridin-2-ol¹ in 5 mL of ethanol was added 0.011 g(0.30 mmol) of sodium borohydride. The reaction mixture stirred at roomtemperature for 20 min. To the solution, 0.108 g (0.18 mmol) of compound5 was added and the reaction was heated at reflux for 5 h. The reactionmixture was concentrated under reduced pressure. The residue wasdissolved in 20 mL of 1 N hydrochloric acid and extracted with three 15mL of ethyl acetate. The combined organics were dried over anhydroussodium sulfate, filtered, and concentrated. The residue was purified byflash chromatography (silica, 0-15% methanol/methylene chloride) toafford 0.075 g (67%) of compound 26a as an off-white solid: MS: Calcd.for C₂₅H₂₃ClF₂NO₅S₂ (MH⁺), m/z=554.1. found 554.3. Retention time: 2.91min.

Note 1: The preparation of 3,3′-disulfanediyldipyridin-2-ol waspreviously described; see Smith, K.; Anderson, D.; Matthews, I.; J. Org.Chem. 1996, 61, 662.

The following compound was prepared analogously:

26b¹: MS: Calcd. for C₂₅H₂₄ClF₂N₂O₄S₂ (MH⁺), m/z=553.1. found 553.0.Retention time: 2.27 min.

Note 1: The preparation of 3,3′-disulfanediyldipyridin-2-amine waspreviously described; see Smith, K.; Anderson, D.; Matthews, I.; J. Org.Chem. 1996, 61, 662.

Step 2

To a stirred solution of 0.075 g (0.14 mmol) of compound 26a in 5 mL ofmethylene chloride was added 0.093 g (0.38 mmol) of 3-chloroperbenzoicacid. The reaction was stirred at room temperature for 3 h. After thistime, the reaction mixture was diluted with 20 mL of methylene chlorideand washed with 20 mL of saturated aqueous sodium bicarbonate. Theaqueous layer was separated and extracted with three 20 mL portions ofmethylene chloride. The combined organics were dried over anhydroussodium sulfate, filtered, and concentrated. The residue was purified byflash chromatography (silica, 0-20% methanol/methylene chloride) toafford 0.055 g (67%) of compound 27a as an off-white solid: ¹H NMR(CD₃OD 300 MHz) δ 8.19 (dd, J=7.3, 2.2 Hz, 1H), 7.79-7.57 (m, 5H),7.29-7.16 (m, 1H), 6.64-6.51 (m, 1H), 6.48 (dd, J=7.2, 6.4 Hz, 1H), 5.05(dd, J=12.8, 2.6 Hz, 1H), 4.41 (d, J=12.3 Hz, 1H), 3.93-3.76 (m, 1H),3.58 (t, J=7.4 Hz, 2H), 3.26 (dd, J=9.9, 2.9 Hz, 1H), 3.03 (t, J=11.9Hz, 1H), 2.56 (d, J=13.6 Hz, 1H), 2.44 (d, J=10.3 Hz, 1H), 2.37-2.17 (m,2H), 1.96-1.79 (m, 1H). MS: Calcd. for C₂₅H₂₂ClF₂NNaO₇S₂ (MNa⁺),m/z=608.0. found 608.5. Retention time: 2.78 min. HPLC (Method 2)>99%(AUC), t_(R)=13.91 min. [α]²⁵ _(D)=−144.0° (c 0.100, MethyleneChloride).

The following compound was prepared analogously:

¹H NMR (CDCl₃ 300 MHz) δ 8.26 (dd, J=4.9, 1.8 Hz, 1H), 7.96 (dd, J=7.8,1.8 Hz, 1H), 7.62 (d, J=8.7 Hz, 2H), 7.51 (d, J=8.8 Hz, 2H), 7.18-7.02(m, 1H), 6.79 (dd, J=7.8, 4.9 Hz, 1H), 6.54-6.40 (m, 1H), 5.86 (s, 2H),5.14 (dd, J=12.7, 2.6 Hz, 1H), 4.36 (d, J=12.7 Hz, 1H), 3.94-3.78 (m,1H), 3.47-3.12 (m, 3H), 3.03 (t, J=11.5 Hz, 1H), 2.59-2.43 (m, 2H),2.43-2.13 (m, 2H), 2.05-1.81 (m, 1H). MS: Calcd. for C₂₅H₂₄ClF₂N₂O₆S₂(MH⁺), m/z=585.1. found 585.0. Retention time: 2.90 min. HPLC (Method2)>99% (AUC), t_(R)=13.93 min. [α]²⁵ _(D)=−156.0° (c 0.100, MethyleneChloride)

Assay

The pharmacological properties of the compounds of this invention may beevaluated by a number of pharmacological assays. The exemplifiedpharmacological assays, which are described later, have been carried outwith the compounds according to the present invention, as well as withsalts thereof.

Gamma-secretase activity was determined as described by Zhang et al.(Biochemistry, 40 (16), 5049-5055, 2001), which is herein incorporatedby reference. Activity is expressed either as a percent inhibition or asthe concentration of compound producing 50% inhibition of enzymeactivity.

Reagents

Antibodies W02, G2-10, and G2-11 were obtained from Dr. KonradBeyreuther (University of Heidelberg, Heidelberg, Germany). W02recognizes residues 5-8 of Aβ peptide, while G2-10 and G2-11 recognizethe specific C-terminal structure of Aβ 40 and Aβ 42, respectively.Biotin-4G8 was purchased from Senetec (St. Louis, Mo.). All tissueculture reagents used in this work were from Life Technologies, Inc.,unless otherwise specified. Pepstatin A was purchased from RocheMolecular Biochemicals; DFK167 was from Enzyme Systems Products(Livermore, Calif.).

cDNA Constructs, Tissue Culture, and Cell Line Construction

The construct SPC99-Ion, which contains the first 18 residues and theC-terminal 99 amino acids of APP carrying the London mutation, has beendescribed (Zhang, L., Song, L., and Parker, E. (1999) J. Biol. Chem.274, 8966-8972). Upon insertion into the membrane, the 17 amino acidsignal peptide is processed, leaving an additional leucine at theN-terminus of Aβ. SPC99-lon was cloned into the pcDNA4/TO vector(Invitrogen) and transfected into 293 cells stably transfected withpcDNA6/TR, which is provided in the T-REx system (Invitrogen). Thetransfected cells were selected in Dulbecco's modified Eagle's media(DMEM) supplemented with 10% fetal bovine serum, 100 units/mLpenicillin, 100 g/mL streptomycin, 250 g/mL zeocin, and 5 g/mLblasticidin (Invitrogen). Colonies were screened for Aβ production byinducing C99 expression with 0.1 g/mL tetracycline for 16-20 h andanalyzing conditioned media with a sandwich immunoassay (see below). Oneof the clones, designated as pTRE.15, was used in these studies.

Membrane Preparation

C99 expression in cells was induced with 0.1 g/mL tetracycline for 20 h.The cells were pretreated with 1 M phorbol 12-myristate 13-acetate (PMA)and 1 M brefeldin A (BFA) for 5-6 h at 37 C before harvesting. The cellswere washed 3 times with cold phosphate-buffered saline (PBS) andharvested in buffer A containing 20 mM Hepes (pH 7.5), 250 mM sucrose,50 mM KCl, 2 mM EDTA, 2 mM EGTA, and Complete protease inhibitor tablets(Roche Molecular Biochemicals). The cell pellets were flash-frozen inliquid nitrogen and stored at −70° C. before use.

To make membranes, the cells were resuspended in buffer A and lysed in anitrogen bomb at 600 psi. The cell lysate was centrifuged at 1500 g for10 min to remove nuclei and large cell debris. The supernatant wascentrifuged at 100000 g for 1 h. The membrane pellet was resuspended inbuffer A plus 0.5 M NaCl, and the membranes were collected bycentrifugation at 200000 g for 1 h. The salt-washed membrane pellet waswashed again in buffer A and centrifuged at 100000 g for 1 h. The finalmembrane pellet was resuspended in a small volume of buffer A using aTeflon-glass homogenizer. The protein concentration was determined, andmembrane aliquots were flash-frozen in liquid nitrogen and stored at−70° C.

γ-Secretase Reaction and Aβ Analysis

To measure γ-secretase activity, membranes were incubated at 37° C. for1 h in 50 μL of buffer containing 20 mM Hepes (pH 7.0) and 2 mM EDTA. Atthe end of the incubation, Aβ 40 and Aβ 42 were measured using anelectrochemiluminescence (ECL)-based immunoassay. Aβ 40 was identifiedwith antibody pairs TAG-G2-10 and biotin-W02, while Aβ 42 was identifiedwith TAG-G2-11 and biotin-4G8. The ECL signal was measured using anECL-M8 instrument (IGEN International, Inc.) according to themanufacturer's instructions. The data presented were the means of theduplicate or triplicate measurements in each experiment. Thecharacteristics of γ-secretase activity described were confirmed usingmore than five independent membrane preparations.

As shown below in the Table, the compounds of the invention had amembrane IC₅₀ in the range of 1 nM to 20 nM.

TABLE

Aβ₄₀ IC₅₀ Compound R (nM)  4

1.4  8a

1.9  8b

6.6 11

1.7 14

5.8 25a

18.7 25b

4.5 25c

5.5 25d

10.2 25e

6.4 25f

2.9 25g

12.9 25h

16.5 27a

2.8 27b

18.0

While the present invention has been described in conjunction with thespecific embodiments set forth above, many alternatives, modificationand variations thereof will be apparent to those of ordinary skill inthe art. All such alternatives, modifications and variations areintended to fall within the spirit and scope of the present invention.

What is claimed:
 1. A compound of Formula (I)

or a pharmaceutically acceptable salt thereof, wherein R is selectedfrom the group consisting of: (1) -pyridinyl, (2) -pyrazolinyl, (3)-1,2,4-oxadiazolyl, (4) -(C1-C2)alkyl-pyridinyl, (5)-(C1-C2)alkyl-pyrazolinyl, and (6) -(C1-C2)alkyl-1,2,4-oxadiazolyl,wherein the pyridinyl, pyrazolinyl, and -1,2,4-oxadiazolyl, isunsubstituted or substited with one L¹ group; R¹ is independentlyselected from the group consisting halogen, (C1-C6)alkyl, —CN, —CF₃,—O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl), —C(O)—O—(C1-C6)—OH-substituted(C1-C4)alkyl, halo(C1-C6)alkyl, —(C1-C4)alkoxy-OH,—(C1-C4)alkoxy(C1-C4)alkoxy and —S(O)₂(C1-C6)alkyl; n is 0, 1, 2, or 3;Ar is selected from the group consisting of phenyl optionallysubstituted with 1 or 2 L² groups, and pyridyl optionally substitutedwith 1 or 2 L² groups; L¹ is independently selected from the groupconsisting of —OCH₃, —NH₂, ═O, and (C1-C5)alkyl; and L² is independentlyselected from the group consisting of halogen, (C1-C6)alkyl , —CN, —CF₃,—O—(C1-C6)alkyl, —O-(halo(C1-C6)alkyl), —C(O)—O—(C1-C6)alkyl,—OH-substituted(C1-C6)alkyl, halo(C1-C6)alkyl, —OH-substituted(C1-C4)alkoxy, —(C1-C4)alkoxy(C1-C4)alkoxy and —S(O)₂(C1-C6)alkyl. 2.The compound of claim 1, wherein n is 2, each R¹ is the same ordifferent halogen, and the R¹ groups are bound to the phenyl moiety asshown in Formula (II):


3. The compound of claim 2, wherein the halogen is fluoro.
 4. Thecompound of claim 1, wherein Ar is selected from the group consisting ofp-Cl-phenyl-, p-CN-phenyl-, p-CF₃-phenyl, pyridyl, and pyridylsubstituted with 1 or 2 substituents independently selected from thegroup consisting of halogen, —(C1-C6)alkyl, —CN, —CF₃, O—(C1-C6)alkyl,—O-halo(C1-C6)alkyl, —C(O)—O—(C1-C6)alkyl, —OH-substituted(C1-C6)alkyl, - -halo(C1-C6)alkyl, -OH substituted (C1-C4)alkoxy and—(C1-C4)alkoxy(C1-C4)alkoxy.
 5. The compound of claim 4, wherein Ar isp-Cl-phenyl.
 6. The compound of claim 1, having the Formula:


7. The compound of claim 6, wherein Ar is p-Cl-phenyl, n is 2, each R¹is the same or different halogen, and the R¹ groups are bound to thephenyl moiety as shown in Formula (II):


8. A compound which is selected from the group consisting of:

or a pharmaceutically acceptable salt thereof.
 9. A compound which isselected from the group consisting of:

or a pharmaceutically acceptable salt thereof.
 10. A pharmaceuticalcomposition comprising the compound of claim 1, or a pharmaceuticallyacceptable salt thereof, and at least one pharmaceutically acceptablecarrier.
 11. A pharmaceutical composition comprising the compound ofclaim 8 or a pharmaceutically acceptable salt thereof, and at least onepharmaceutical acceptable carrier.
 12. A pharmaceutical compositioncomprising the compound of claim 9 or a pharmaceutically acceptable saltthereof, and at least one pharmaceutical acceptable carrier.